What ageing looks like in a corydoras
A well-kept corydoras can live far longer than the few years many owners expect — a decade is entirely possible — and old age in these fish is gradual. The young cory's constant bustling along the bottom gives way to longer rests in a favourite spot, shorter foraging trips and less interest in the mid-water dashes the group makes to the surface. Colours may soften and the body can look a little thinner behind the head even in a healthy fish. None of this is illness by itself; it is the tempo changing. What matters is the baseline: an old fish that still comes out to feed with the group, rests upright and breathes calmly is ageing well, and knowing what its normal looks like is what lets you spot the day it changes.
Substrate and water: soften the edges
If an ageing cory still lives on sharp gravel, now is the time to change its world: barbels — the whiskers it tastes the bottom with — wear and fray on rough substrate, and older fish heal more slowly from that wear. A layer of smooth sand over or instead of gravel lets an old cory forage the way it is built to, sifting without damage. Water stability matters more with age too. An old fish tolerates a late water change or a temperature wobble less gracefully than it did at two years old, so smaller, more regular changes beat heroic occasional ones, and the temperature should be held steady rather than allowed to drift with the room. Gentle filtration flow helps as well; a senior cory should not have to fight a current to cross its own tank.
Feeding an older bottom dweller
The commonest problem for a senior cory is not appetite but access. Younger, faster fish — including its own grandchildren in a breeding tank — reach sinking food first, and an old cory that arrives politely late finds the wafer already gone or guarded. Feed the tank, then place a small sinking pellet or a piece of wafer directly near the old fish's resting place, ideally as the lights go down, when corys naturally forage and competition sleeps. Soft foods are easier for an old fish than hard dry pellets, and variety — a little thawed bloodworm or daphnia alongside the staple — keeps condition on a fish that eats smaller meals than it used to.
Watching for the changes that matter
Barbels worn down to stubs, a fish that stops joining the group at feeding, rapid breathing at rest, or white patches and frayed fins on a fish that has always been clean are the senior changes that deserve an aquatic vet's opinion rather than watchful waiting — in an old fish, treatable problems are worth treating early, and 'he is just old' should be a conclusion, not a first guess. Write down what you see, with dates: when the appetite dipped, when the resting spot changed, what the water tests showed. That running record is exactly what a consultation runs on, and keeping it in KinsLe's Pet Passport — alongside the fish's age, group history and water routine — means the whole of the cory's long life is in one packet when it is needed.